Centrifugal separator



Jan. 21, 1958 H. c. FITZSIMMQNS 2,820,589

v CENTRIFUGAL SEPARATOR Original Filed Oct. 20, 1952 3 sheetsheet 2 54 INVENTOR.

a MM Jan. 21, 1958 H. c. FlTZSlMMONS CENTRIFUGAL SEPARATOR 3 Sheets-Sheet 3 Original Filed Oct. 20, 1952 United States Patent CENTRIFUGAL SEPARATOR Harold C. Fitzsimmons, West Chester, Pa., assignor to The Sharples Corporation, Philadelphia, Pa., a corporation of Delaware Continuation of abandoned application Serial No. 315,725, October 20, 1952. This application March 23, 1956, Serial No. 573,385

6 Claims. (Cl. 233-20) This invention relates generally to centrifuges, and it relates particularly to centrifuges of the type designed to effect sedimentation or separation of solids from liquids. For convenience the solids or high-density material will be referred to herein as sludge, and the lower-density materials will be called the liquid, although it is to be understood that the liquid may be separated by the centrifuge into various phases of different densities. Thus, the primary purpose of the centrifuge may be to remove sludge from a liquid, or the removal of sludge may be incidental to the centrifugal separation of the liquid into two or more phases.

This application is a continuation of the prior application for Harold C. Fitzsimmons for Industrial Process and Apparatus, Serial No. 315,725, filed October 20, 1952, and now abandoned.

It has heretofore been proposed to remove sludge from a rapidly rotating centrifuge rotor through a plurality of sludge valves spaced around the periphery of the rotor, the inner surfaces of the rotor sloping toward the valves in order that the sludge will be carried to the valves by centrifugal force.

In machines of this kind, the valves are usually operated by fluid pressure or other motors to discharge the accumulated sludge periodically. In the design of such a centrifugal separator it is important that an arrangement be provided which is durable, and capable of operating over a long period of time without damage to the valve disc or valve stem or valve seat, While being sealed against leakage at all times when the valve is in a closed position. In the past, however, these results have not been attained because in the prior art-constructions when the valves are moved to their closed position the large centrifugal force generated by the mass of the valve operating parts is imparted directly to the valve element and seat in hammer-like blows which cause rapid wear and damage to these parts.

With the foregoing in mind, the principal object of the present invention is to provide an improved sludge valve construction for centrifuge machines in which the valve parts are not subject to rapid wear and damage caused by heavy hammer-like blows imparted to them by closing of the valve.

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Fig. 2 is a horizontal sectional view taken just above the sludge valves of Fig. 1 with other parts omitted;

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Fig. 3 is an enlarged sectional view of one type of sludge valve assembly taken on the line 3-3, Fig. 1;

Fig. 4 is a fragmentary sectional view similar to Fig. 3 showing the valve in open position;

Fig. 5 is a sectional view taken on line 55, Fig. 3; and,

Fig. 6 is an enlarged detached perspective view showing a detail of the construction of the sludge valve bushing.

Referring to the drawings, the invention in one form has been shown as applied to a centrifuge 10. The rotor 11 is driven by a shaft 12, mounted for rotation within a support 13, and itself driven by any suitable form of motor, not shown. The rotor 11 is secured to a sleeve 14 which is secured to and rotates with shaft 12.

The mixture of liquids and solids supplied through a feed or inlet pipe 15 flows downwardly through the space between tube 16 and sleeve 14 and outwardly below the skirt 17 of tube 16. The easily separable solids move into the space or chamber 20 formed by the inclined walls 21 and 22 of the rotor 11. Efficient separation or sedimentation of the remaining solids takes place as liquid flows inwardly of the stratifying discs 23 and the sludge or heavier solid material flows outwardly therefrom. The liquid flows upwardly in the space ad acent the periphery of tube 16 and over a ring dam 24 for discharge by way of stationary outlet 25.

Sludge collecting anywhere in the region of intersection of walls 21 and 22 is discharged through openings 26 of a plurality of bushings 27 and is deflected downward by a conical skirt or ring 30 and is discharged from a chute 31. The deflecting skirt 30 may be supported in any suitable way such as by bolts 32 extending through the stationary housing.

Associated with each of the plurality of bushings 27, ten of them being shown in Fig. 2, is a sludge valve assembly 33. Each such assembly has connected thereto a tube or pipe 34 forming a passageway in flow communication with an external source of an auxiliary liquid. in Fig. 1 the auxiliary liquid from a supply pipe 35, under control of a manually operable valve 36 of the fast-opening and closing type, is directed upwardly by a spray ring 37 into proximity with the overhanging lip 40 of a cup 41 secured to the rotor 11. The ring 37 is supported as by a'bracket 42 secured to the stationary support 13.

In accordance with the present invention, upon opening of the valve 36, as by a lever 43, liquid is directed through each of a plurality of openings 44 toward the inner edge of lip 40 and into the annular recess formed thereby. With the aid of a plurality of fins 46, the auxiliary liquid is quickly brought up to the speed of the rotor 11. The liquid flows upwardly through each flow channel 47 into one of the connecting passageways or tubes 34.

Before valve 36 of Fig. 1 is opened to admit the auxiliary liquid, centrifugal force, due to the high speed rotation of rotor 11, is efiective in maintaining the valve element 50 firmly seated against the valve seat 51 at the inner end of bushing 27. The valve seat 51 may be formed in a removable insert 52 of suitable wear-resistant material.

Each valve-operating assembly 33 is supported by the disposed surface 53 of the valve body 55 (see Fig. 1).

Referring to Fig. 3 of the drawings, it will be seen that the pipe or tube forming passageway 34 is connected in flow communication with a channel 54 in valve body 1 .55 whi hl ad by way o ope ing .56 i cy i r1 2 57 into chamber 58 of the cylinder 60. From a branch.

of channel 54 liquid may flow to an orifice or leak-port 61 formed in a member 62 snugly fitting into a leak bushing 63 threaded into the valve body 55. A flat end of bushing 63 engages a flat surface of bushing 64 inserted into the rotor 11, and the :opening in rotor 11 in which .the bushing 64 is located is closed by a screw plug 74. A seal ring 65 is'providedfin the region of the .flaredend of bushing 64 to 'form a Iiquid-tight'connection. Leakage liquid flows downwardly through a passage 67 closed at .its lower end by screw plug 70, Fig. 5,, and outwardly through opening 71 of rotor 11, two of such openings .71 appearing in Fig. 1. Withfurther reference to Fig. 1, it will 'be seen 'that the leak openings '71 are disposed below the upper edge of skirt or annular member .72 of the frame,- and the auxiliary liquid .is thus kept from mixing with the sludge discharged above the upper edge of .member 72. The auxiliary liquid is discharged from the centrifuge .through passage 73.

Movement ofeach valve element 50 withrespect -to .its seat {5.13s .accomplishedby a piston 75 which is operatively connected to the valve element 59 as herein- .after .set forth; The ,piston 75 is provided with a skirt 76, the .inner finished .surface of which slides in substantially liquid-tight engagement with a packing orpiston ring 77 supported .by the cylinder 60. The piston skirt 176a1so slides upon the outer wall 80 of the cylinder member .60 which is provided with an outer peripheral flange .81 engaging an annular sealingring 82.

' The cylinder plug 57 has areduced .end ,portion which fits .into the recess of a cup .83 whose :base .engages against aagasket or :seal 84 which is seated on a flatsurface 'portion'of body 55. When the centrifngeis operating, centrifugal force urges the respective parts .81 .and 83 outwardly against the seals .82 :and ;84, the cylinder plug 57 having'suflicient :mass to insure .a liquid-tight seal at the ring 84. :Of course, the plug 57 is free to move outwardly relative to cylinder 60.

While .little leakage may be anticipated between :ring 77 and the skirt 76 of piston 75, provision is made to prevent accumulation .of .liquid :between the outer face of the piston 75 and the ,cap or :cylinder :head 86. This is accomplished by providing i3. passage 87 in the body .55 which ,is .in flow communication between the space at the outer side of themis-ton .75 and 1he;opening 88 through a bushing 90 which in turn abuts a bushing 91 in the rotor 11, a sealing .ring 9,2 being :provided .toenga-ge the ."flared end of bushing .91. Any accumulation of liquid at the outer .face of the ,piston 75 is discharged through the bore .93 of bushing :91. Cylinder head 36 is secured in place by means of bolts, .as shown, .or other suitable I means. Carried by the. piston 75 is :a valve rod or stem 34 which extends through aligned (openings "in cylinder pluga57 and cup 8:3, the :latter having :a :recess in which there is disposed packing or .a sealing ring -95. Centrifugal force :and fluid :pressnre acting upon the packing or seal ring 95 Zkeeps it in zliquid-tight sealing relation with piston stem 94 and the adjacent enclosing wall.

Connection between the valve element 50 and the valve stem or rod 94 is reflected by means of a tubular :sleeve197 which provides a 'lost-motion'connection between :stem '94 and the element 50. The inner end of fthe sleeve 97 is telescoped over the end portion of the against displacement therefrom by end wall portions 102; By this construction the valve element 50 is af- .4 .forded hmitedm vemen axi lly with respect to theslee e 97 and stem 94. 7

Assume that valve 36 is opened to admit auxlhary liquid to the annular chamber formed by the hp 40. As the liquid comes up to speed, it flows upwardly through channel 47 and outwardly through passageway 34 to the inner chamber 58 of the valve cylinder 60. Within a short interval of time, of the order of a tenth of a second, the pressure head exerted by the liquid in the passageway 34 upon the inner "face of piston 75 due to centrifugal force .on this liquid operates to actuate the piston 75 to the right with respect to Fig. 3, thus unseating -the element iSOtrom its seat-51 and opening the valve to discharge sludge or solid .material outwardly through openings 26 of bushing 27.

Referring to Fig. .6 :of the :drawings, radially-extending recesses 104 :are provided in the face of the enlarged head portion of bushing 27. These recesses permit the solids or sludge :to reach gthfi discharge opening through the bushing 27 while the valve sleeve 97 is-still within the central ,bore 105 of the enlarged head portion of .said bushing27, for example, asshown in Fig. 4 of thedrawings. The outward how 'of the separated solids due to the sedimentation that/has taken place is rapid due to the magnitude of the centrifugal force exerted thereon.

In operation of the centrifuge all of the valve assemblies 33, as shown in Fig. "2, are simultaneously operated and after deflection by skirt 3.0, the sludge is rapidly discharged from chute '31. The valves need be opened for only a short interval of time and only long enough.

to empty the chamber *20 of solids. By suitably ,COH. trolling the supply valve 36, Fig. 1, loss of, liquid from rotor 11 may be minimized. The supply valve 36 :may be and preferably is automatically opened and closed by a timing mechanism of any suitable type, of which there are several readily available on the market and known to those skilled in the art. In this manner the open and closed times may "be selected in conformity with the requirements of the process, Whether the main function of the centrifuge be the recovery of sludge present in large quantity. or whether-it be clarification of liquids containing only a small amount of sludge.

While the sludge valves are in open position, it will be understood that auxiliary liquid is continuously discharged through orifice 61, but since the admission of liquid is at a rate materially greater than its .flow through orifice 61 this orifice does not atiect valve operation. However, as soon .as supply valve '36 is closed, the passageway ,34 is quickly emptied lthrOughorifice .61 and, in a time interval of the order of one-tenth of 'a second after closure of supply valve 36 :the piston 75, stem 94 and sleeve 97 are caused to move outwardly under the influence of centrifugal fol Q until the skirt 76 impinges the .fiange 81 of cylinder 60, which will arrest this motion. Due to the lost-motion .connection between the stem 94 and valve element 50, the latter will .continue to move outwardly under the influence of centritugal force until it seats in valve seat 51.

Since the operation .of the valves is regulated in relation to the accumulation of solids in the :rotor, the frequency of the functioning of the valves may vary widely, dependin on the percentage of solids present in the liquid being centrifuged. The valves'may, therefore, operate .once every few minutes, or once every few seconds. By means of the lostemotion connection between the valve element 50 .andrstem ,94 and the positive limit to movement of the piston 75 provided by the cylinder flange 81, the large centrifugal :force engendered by the Weight of the stem .94 and piston 75 is not transrn'itted .to the valve element or by the-latter to the valve seat 51. As a result, the engagement of the valve element 50 with valve .seat 51 is .solely the result of centrifugal 'force exerted :on the valve element 550 itself. This force is adequate to create a leakproof seal between the valve parts, but it is every much reduced blow upon the valve seat with the resultthatthe motor ,may operate at high frequencies over long periodofitlme without damage to the valve element 50 and'the valve seat 51 which has been found to result in' cases where the valve parts are subjected to the full impact of the force generated by the piston and its stem. In addition, since the flange 81 positively limits travel of the piston 75 as set forth no large stresses are developed in the small diameter stem 94 with the result that the possibility of the stem being bent or otherwise damagedis entirely eliminated.

Although the above is illustrative of the practice of this invention in relation to a particular representation of valve, its use is not limited to any one type of valve, but it may be generally applied to diflferent constructions, one of which is illustrated in U. S. Patent No. 2,286,354. Its usefulness does not depend upon whether the valve is actuated by a feed of valve operating liquid as described above, or whether the valve is opened or closed by such an auxiliary liquid, or whether the operation of the valve is automatic in relation to a build-up of solids as described in U. S. Patent No. 2,286,354. It may be applied with advantage wherever a motor-operated valve is subject to the influence of centrifugal force.

While preferred embodiments of the invention have been described herein, modifications thereof may be made within the spirit and scope of the invention as set forth in the following claims.

I claim:

1. In a centrifuge having a rotor for effecting centrifugal sedimentation of solids from a mixture thereof with liquid, means defining a radial discharge passage through the wall of the rotor, a valve seat within said rotor at the inner end of said passage, a valve element of small mass movable coaxially of the valve seat and normally urged into closing engagement with said valve seat by centrifugal force acting thereon, a piston comparatively greater mass movable coaxially of the discharge passage to and from an outer limit position to which it normally is urged by centrifugal force acting thereon, means connecting the valve element to said piston providing axial movement of said valve element relative to the piston between predetermined fixed inner and outer limits, said valve element when engaged upon said valve seat being spaced outwardly from the inner limit of its movement relative to the piston so that seating engagement of the valve element upon the valve seat is effected independently of the piston by the centrifugal force acting solely on the small mass of said element.

2. In a centrifuge having a rotor for effecting centrifugal sedimentation of solids from a mixture thereof with liquid, means defining a radial discharge passage through the wall of the rotor, a valve seat within said rotor at the inner end of said passage, a valve element of small mass movable coaxially of the valve seat and normally urged into closing engagement therewith by centrifugal force acting thereon, a piston of comparatively greater mass movable coaxially of the discharge passage to and from an outer limit position to which it normally is urged by centrifugal force acting thereon, means connecting the valve element to said piston providing axial movement of said valve element relative to the piston between predetermined fixed inner and outer limits, said valve element when engaged upon said valve seat being spaced outwardly from the inner limit of its movement relative to the piston so that seating engagegent of the valve element upon the valve seat is effected independently of the piston by the centrifugal force acting solely on the small mass of said valve element, and means to effect actuation of the piston inwardly of the rotor from its outer limit position to disengage the valve element from said valve seat and open the discharge passage.

3. In a centrifuge having a rotor for effecting centrifugal sedimentation of solids from a mixture thereof with liquid, means. defining a radial discharge passage through the wall of the rotor, a valve seat within saidrotorv at-the inner end of said passage, a valve element of small mass movable coaxially of the valve seat and normally urged into closing engagement with said valve seat by centrifugal force acting thereon, a piston of comparatively greater mass movable coaxially of the discharge passage to and from an outer limit position to which it normally is urged by centrifugal force acting thereon, means connecting the valve element to said piston providing axial movement of said valve element relative to the piston between predetermined fixed inner and outer limits, said valve element when engaged upon said valve seat being spaced outwardly from the inner limit of its movement relative to the piston so that seating engagement of the valve element upon the valve seat is effected independently of the piston by the centrifugal force acting solely on the small mass of said valve element, and means to effect actuation of the piston inwardly of the rotor from its outer limit position, said valve element in its closed position being adjacent the outer limit of its movement relative to the piston so that actuation of the piston from its outer limit position in turn actuates the valve element inwardly to disengage the same from said valve seat and open the discharge passage.

4. Apparatus as claimed in claim 2 wherein the means connecting the valve element to the piston comprises a tubular sleeve connected at its inner end to said piston and having at its outer end an opening of smaller size than the bore of the sleeve, and the valve element has a head portion mounted for axial movement within the sleeve, the said head portion of the valve element being larger than the opening in the outer end of the sleeve to prevent displacement of the valve element therefrom and provide a fixed limit for outward movement of said element axially with respect to the piston.

5. In a centrifuge having a rotor for effecting centrifugal sedimentation of solids in admixture with liquid, a plurality of circumferentially spaced radial discharge passages through the wall of said rotor, a valve seat at the inner end of each of said discharge passages, a plurality of valve elements of small mass, each valve element being movable coaxially of an associated valve seat and normally urged into closing engagement therewith by centrifugal force acting thereon, a plurality of valve stems, each valve stem positioned coaxially of a separate discharge passage, each said valve stem being movable coaxially of its associated discharge passage to and from an outer limit position to which said valve stem normally is urged by centrifugal force acting thereon, a lost-motion connection between each said valve element and the associated valve stem providing limited axial movement of each said valve element relative to its associated valve stem, each said valve element when engaged upon its associated valve seat being in lost-motion position with respect to its associated valve stem so that seating engagement of each valve element upon its associated valve seat is effected independently of its associated valve stem by the centrifugal force acting solely on the small mass of said valve element, and means for effecting actuation of each said valve stem inwardly of the rotor from its outer limit position to disengage its associate-cl valve element from its associated valve seat to open said discharge passages.

6. In a centrifuge having a rotor for effecting centrifugal sedimentation of solids from an admixture of solids and liquid, a radial discharge passage through the wall of said rotor, a valve seat at the inner end of said discharge passage, a valve element of small mass, said valve element being radially movable with respect to said valve seat and normally urged into closing engagement therewith by centrifugal force acting thereon, radially movable valve oper ating means normally urged radially outward by centrifugal force acting thereon, means for limiting the radial outward travel of said valve operating means, a lost- 7 v 8 a mbfion mnmxina between said valv elemen and sai ally iinw rilly qf the into: from it's pa limit position "to Waive pfl t g 'rme ns pr vi g limited mo emen of di en g s id aiv el ment from said valve seatjtq open said valve element relative to said valve operating means, Said dischai'gepassage. said vailveelement when engaged upon said valve seat being in' lost-motionposi-tion with respect to said valve 5 5 References Citediin ine file of thi pa :operafingmeans so hat seating engagement of said valve element-upon said valve seat is effeefed independently of I UNITiEDETATES PATENTS 'said valve operating means by centrifugal force "acting 22816354 *Fitzsimmqns June 16, 1942 solely on the sma ll massof-said valve element, and-means 2,286,355 Fitzsimmons June 16, 1942 forlefiecting actuation of said valve operating means radi- '10 2,343,806 SCOfield Mar. 7, 1944 

